Alarm management systems carried onboard aircraft are generally charged with the generation, the verification of fault or information messages, and the delivery of instructions to the pilot. Today, these systems are becoming increasingly complex and are linked with a large number of critical systems.
At the outset, the information was provided to the pilot in the form of telltale or flashing lights, optionally associated with texts that the pilot was able to read on a monitoring screen. One of the problems related to these telltale lights resides in their directional aspect: there is a risk of them not being seen. Audible alarms, such as sirens, or quasi-audible alarms, such as vibrating sticks, which made it certain that the pilot had acknowledged them, appeared later.
Currently, with the aim of improving pilot aids, alarm management systems comprising voice synthesis devices are being developed. Explicit announcements can thus be made, enabling the pilot to concentrate exclusively on pure piloting. For example, during a landing manoeuvre, the altitude of the aircraft can be regularly announced to the pilot, who is therefore no longer constrained to watch his altimeter.
In this context, it is sought to provide the pilot with more and more information in the form of announcements on the basis of voice syntheses. The difficulties to be resolved pertain on the one hand to the availability of the audible information and on the other hand to the risks of ambiguity related to overly complex or overly numerous announcements. These issues are critical since the audible announcements may be directly interpreted by the pilot and give rise to an action on his part. The integrity of the announcements made is therefore paramount.
Consequently, onboard alarm management systems conventionally comprise several independent devices for generating voice announcements. In parallel, they integrate a simple priority management device which selects the priority device for generating voice announcements.
Current systems are generally based on a binary item of information related to the presence or otherwise of energy at the output of a device for generating voice announcements and bound for a loudspeaker. The main drawback of this technique resides in the risk that fault modes of equipment belonging to the sound generating chain, typically amplifiers, generate noise. If this spurious noise is emitted at the output of the priority device for generating voice announcements, it will remain active. In the case where it failed to detect a nevertheless substantiated fault, the latter would not be announced even if another device for generating voice announcements has detected it. The consequences may therefore be critical.
Another undesirable effect also appears in this case: the noise generated by a fault mode, for example an amplifier fault mode, is emitted by the loudspeaker, broadcasting an unpleasant sound in the cockpit.
In order to alleviate the drawbacks explained above, the invention proposes a method and a device for detecting the digital origin of an analogue signal aimed at guaranteeing the integrity of the voice announcements made to the pilot by way of an alarm management system.